watercrunch: Hudson's Dredging Hardware Revealed

Last Friday with lots of fanfare a single scoop of PCB enriched sediment was dredged from the bottom of the Hudson River. By some estimates 1.3 million pounds of PCBs, or polychlorinated biphenyls, entered into the upper Hudson from two General Electric factories for three decades before they were banned, in 1977.

While the media concentrated on the history and significance of this event, I don't there was sufficient shock and awe to the mechanics of the dredging operation. This six year dredging operation is unique in its size and scope.

First, a breakdown of the dredging hardware:

1. Environmental Clamshell Bucket. The excavators are equipped with environmental clamshell buckets that seal and minimize overspill. The Environmental Clamshell Bucket differs from traditional dredging buckets by allowing water to pass through its top moveable vents as it submerges, thereby contributing to the reduced turbidity.

2. Flexifloat barges. This is the swiss army knife of all barges. Modular deck barges attach to one another and can be configured in many ways. This is a simple, quick and economical method of moving all types of construction material on water. They even have been used as floating bridges.

3. Dredge. A dredge consists of an excavator on one of the Flexifloat barges. Up to 12 dredges will operate in and around the dredging area at any time.

4. Hopper barges. Seventeen barges will be used to transport the sediment dredged from the river to the treatment facility. Each barge can hold 100 tons of sediment. The barges were transported all the way from Louisiana.

5. Tugboats. Eighteen new tugboats will be used to push the barges to the project areas and to the Processing, Treatment and Transportation Facility.

6. Miscellaneous Survey, Crew, Support Boats. They will use these various vessels for getting to the dredging sites, testing and monitoring, and oversight. Survey crews check monitoring equipment this past Friday in the picture below.

Next blog post, I will try to breakdown what happens to the contaminated soil.

Related Post: Deconstructing Dredging Equipment For the Coal Ash Spill